台灣粗榧及台灣穗花杉之活性成分研究及黃圜酮衍生物的降壓和血管擴張活性之探討

本研究乃是將台灣粗榧(Cephalotaxus wilsoniana)與台灣穗花杉(Amentotaxus formosana)分別進行成分分離及生物活性探討，以及黃圜酮衍生物(Xanthone derivativies)之活性探討。由台灣粗榧(Cephalotaxus wilsoniana)葉部及心材的氯仿抽出物分離得到十二個化合物，其中包含八個已知化合物， C-3-epi-wilsonine (2)、taiwanhomoflavone-A (3)、taiwanhomoflavone-B (4)、ginkgetin (5)、apigenin (6)、?涀-sitosterol (8)、ergosta-4,6,8(14),22- tetraen-3-one (9)、stigmasterol (10)及四個新的化合物C-3-epi-wilsonione (1)、taiwanhomoflavone-C (7)、ergostane-3a,23??-diol (11)與desmethylcephalotaxinone stereoisomer (12)。將以上所得到的部份化合物分別進行細胞毒殺作用，結果顯示，C-3-epi-wilsonione (1)對Hep G2, MCF-7, Hep 3B及HT-29之抑制作用，有concentration-dependent關係，其IC50值分別為145.7, 117.6, 145.7及68.3 ?嵱/ml。台灣穗花杉(Amentotaxus formosana)的心材及皮部利用氯仿萃取進行成分分離，得到十一個化合物，包含九個已知化合物，beta-sitosterol (8)、4-hydroxybenzaldehyde (13)、ent-8(14),15-sandaracopimaradiene-2a,18-diol (14)、amentotaxin WB (15)、stigmasterol-3-O-b-D-glucoside (16)、sandaracopimaraic acid (18)、8(14),15-sandaracopimaradiene-2a,18,19-triol (20)、junipediol A (21)，二個新化合物8(14),15-sandaracopimaradiene-2a, 3b,18-triol (17)、2a,18-dihydroxy-8(14),15-sandaracopimaradiene-7-one (19)。將以上所得到的部分化合物分別進行抗發炎活性篩選，結果顯示，ent-8(14),15-sandaracopimaradiene-2a,18-diol (14)，8(14),15-sandaracopimaradiene-2a,3b,18-triol (17)，8(14),15-sandaracopimaradiene-2a,18,19-triol (20)，對mast cells之脫顆粒反應並無抑制作用，但對rat neutrophils以fMLP/CB所引發?涀-glucuronidase及lysozyme之釋放具有很強之抑制作用，且呈現concentration-dependent關係，其IC50值分別為8.4 ?b 2.9、14.6 ?b 2.6和5.5 ?b 1.8、14.2 ?b 2.8及19.2 ?b 3.3、23.5 ?b 6.3 ?嵱。化合物17, 20對fMLP/CB和PMA誘發neutrophil 產生superoxide anion具有顯著之抑制作用，其IC50值分別為12.6 ?b 1.2、9.4 ?b 1.7和10.7 ?b 3.3、12.9 ?b 0.9 ?嵱。化合物14, 17, 20對NO及TNF-?悒穻豕繭L特別明顯抑制，僅化合物17對N9 cells以LPS/IFN-?袘今oTNF-?悛漣峖芋A具些許抑制作用(44.0 ?b 7.5% inhibition at 30 ?嵱, P＜0.05)。由以上結果可知ent-8(14),15-sandaracopimaradiene-2a,18-diol (14), 8(14),15-sandaracopimaradiene-2a,3b,18-triol (17)和8(14),15-sandaracopimaradiene-2a,18,19-triol (20)之抗發炎性質乃是抑制老鼠嗜中性白血球之活化而產生作用。過去在天然物或合成方面，均已報導黃圜酮類具有抗血栓、抗癌及抗炎作用。為進一步探討化學合成品是否具有心血管作用，擬繼續針對十一個黃圜酮類(xanthones)，3-hydroxyxanthone (22)、1,3-dihy- droxyxanthone (23)、2,3-dihydroxyxanthone (24)、3,4-dihydroxyxanthone (25)、1,6-dihydroxyxanthone (26)、2,6-dihydroxyxanthone (27)、3,5- dihydroxyxanthone (28)、3,6-dihydroxyxanthone (29)、1,3,6,7-tetrahydro- xyxanthone (30)、2,3,6,7-tetrahydroxyxanthone (31)、3,4,6,7-tetrahydro- xyxanthone (32)。二個黃圜酮類氧基丙醇胺類化合物(xanthonoxyprop- anolamines)，3-[3-(propylamino)-2-hydroxypropoxy]-xanthone (33)與 3-[3-(isopropylamino)-2-hydroxypropoxy]xanthone (34)，進行心臟血管系統的活性抑制評估。所有篩選的化合物在老鼠之降壓實驗中，均呈現有效的活性。根據上述實驗發現，具有基本xanthones骨架，三位碳上側鏈有oxypropanolamine取代的化合物，具有明顯提昇降低血壓活性。在大鼠離體胸主動脈(thoracic aorta)血管鬆弛活性試驗中，大部分篩選的化合物對高鉀離子溶液(Ca2+ in high K+)或者由正腎上腺素(norepinephrine, 3 ?嵱)所誘發胸主動脈的瞬間(phasic)和持續性(tonic)血管收縮反應，具有顯著地抑制作用。另外，對phenylephrine及高鉀所誘發的45Ca2+內流，以黃圜酮衍生物34，最具選擇性抑制效果。已知化合物34為一??-腎上腺性阻斷劑。在藥物或迷走神經切斷實驗對血壓及心跳調節方面，結果顯示，化合物30，並不被膽素性神經及迷走神經所影響。綜合以上結果認為，化合物34對高鉀和norepinephrine在胸主動脈所產生血管收縮反應，主要乃是抑制了voltage-dependent和receptor-operated calcium channel這二個通道的Ca2+內流。因此，化合物 34的血管鬆弛特性，是因為阻斷Ca2+通道以及-腎上腺性作用所導致。

關鍵字

活性成分研究；台灣粗榧；台灣穗花杉；黃圜酮衍生物

並列摘要

In a research of bioactive constituents of Cephalotaxus wilsoniana, eight known compounds, C-3-epi-wilsonine (2), taiwanhomoflavone-A (3), taiwanhomoflavone-B (4), ginkgetin (5), apigenin (6), ??-sitosterol (8), ergosta-4,6,8(14),22-tetraen-3-one (9), stigmasterol (10) and four new comounds, C-3-epi-wilsonione (1), taiwanhomoflavone-C (7), ergostane-3??,23??-diol (11) and desmethylcephalotaxinone stereoisomer (12), were isolated from the leaves and heart woods, respectively. Their structures were characterized by spectroscopic and chemical methods. Compound 1 showed cytotoxic activity against the Hep G2, MCF-7, Hep 3B and HT-29 in a concentration-dependent manner with IC50 values of 145.7, 117.6, 145.7及68.3 ?嵱/ml, respectively. In a continous research of bioactive principles of Formosan plants, nine known compounds, ??-sitosterol (8), 4-hydroxybenzaldehyde (13), ent-8(14),15-sandaracopimaradiene-2??,18-diol (14), amentotaxin WB (15), stigmasterol-3-O-??-D-glucoside (16, 16), sandaracopimaraic acid (18), 8(14),15-sandaracopimaradien-2??,18,19-triol (20), junipediol A (21) and two new compounds, 8(14),15-sandaracopimaradiene-2??, 3??,18-triol (17), 2??,18-dihydroxy-8(14),15-sandaracopimaradiene-7-one (19) were isolated from the heart woods and barks of this plant, respectively. The anti-inflammatory activities of 14, 17, and 20 was assessed in vitro by determining their inhibitory effects on the chemical mediators released from mast cells, neutrophils, macrophages, and microglial cells. Compounds 14, 17, and 20 showed significant concentration-dependent inhibitory effects on the release of ??-glucuronidase from rat neutrophils in response to formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB) with IC50 values of 8.4 ?b 2.9, 5.5 ?b 1.8 and 19.2 ?b 3.3 ?嵱, respectively. Compounds 17 and 20 also showed significant concentration-dependent inhibitory effects on superoxide anion generation in rat neutrophils stimulated with fMLP/CB and phorbol 12-myristate 13-acetate (PMA) with IC50 values of 12.6 ?b 1.2 and 9.4 ?b 1.7, and 10.7 ?b 3.3 and 12.9 ?b 0.9 ?嵱, respectively. A series of xanthones and xanthonoxypropanolamines have been synthesized. The activity of compounds on cardiovascular system was evaluated. All the compounds tested exhibited effective hypotensive activity in anesthetized rats. An oxypropanolamine side chain substituted at the C-3 position of the xanthone nucleus significantly enhanced the hypotensive activity. In rat thoracic aorta, all the compounds tested significantly depressed the contractions induced by Ca2+ (1.9 mM) in high K+ (80 mM) medium and the phasic and tonic contractions caused by norepinephrine (3 µM). In the rat thoracic aorta, the phenylephrine– and high K+– induced 45Ca2+ influx were both inhibited by a selective xanthone derivative, 34. In addition to the previously reported result of 34, evaluated as beta adrenoceptor blocker, the depressor and bradycardia effects of 30 are independent of the parasympathetic passway. These results suggest that 34 showed inhibitory effects on the contractile response caused by high K+ and norepinephrine in rat thoracic aorta are mainly due to inhibition of Ca2+ influx through both voltage-dependent and receptor-operated Ca2+ channels. The vasodilating properties of 34 is due to its calcium channel and beta adrenergic blocking effects.